Conventionally, there is known an extraneous-matter detecting apparatus that detects an extraneous matter and the like adhered to a lens on the basis of an image captured by a camera arranged at the outside of a vehicle, for example. There is proposed a technology of the extraneous-matter detecting apparatus for detecting an extraneous-matter region that indicates adhesion of the extraneous matter on the basis of a luminance distribution of the captured image, for example (see Japanese Laid-open Patent Publication No. 2005-084959, for example).
However, in the conventional technology, there exists a case where, for example, an abnormality in the illuminance of lights being made incident on a camera, such as incidence in a backlight state, and the extraneous-matter region are not able to be individually detected, in some cases. Therefore, the conventional technology has room for improvement in improving the detection accuracy of an extraneous matter.